A practical method for the high-precision displacement measurements of the three degrees of freedom-compliant mechanisms based on computer micro-vision is proposed. The method consists of two steps. In the first step, the candidate pixels are selected using a ring projection transform matching approach. In the second step, the exact location is determined by an improved pseudo-Zernike moment method. The setup of the micro-vision system is also introduced. A series of simulations is carried out and the results show that the proposed algorithm enjoys extremely high precision and robustness in the presence of image translations and rotations. Finally, a micro-vision system and a laser interferometer measurement (LIM) system are built up to validate and compare the actual performances of the proposed method. The experimental results demonstrate that the proposed approach can obtain a high accuracy and shows higher operability and stability than the LIM system. Moreover, the measuring accuracy can reach a pixel.